Foaming liquid dispenser

1. A foaming pump mechanism for dispensing a foam which comprises:

a liquid cylinder in fluid communication with a supply of a liquid composition and in fluid communication with a dispensing nozzle, the liquid cylinder further including a bore and a liquid cylinder piston moveable with the bore;

an air cylinder in fluid communication with the dispensing nozzle,

the dispensing nozzle includes an a liquid inlet port, an air inlet port, further downstream thereof a single screen and a delivery outlet,

wherein the volumetric ratios of the volumes of the liquid cylinder and the air cylinder between the base and peak of the stroke cycles is between 1:0.1-25,

wherein a first mixing region of the dispensing nozzle is adapted to mix the liquid composition and air to produce a mixed air and liquid composition

further wherein the first mixing region includes a circular sidewall and an inwardly extending circumferential skirt wall which depends from the circular sidewall, and

wherein the single screen extends across a flow path of the mixed air and liquid composition in a second mixing region of the dispensing nozzle and is adapted to comminute the mixed air and liquid composition and forms a foam therefrom, such that the mixed air and liquid composition is present on a side of the single screen proximal to the second mixing region and the foam formed by the single screen is present on the opposing side of the single screen.

2. The foaming pump mechanism according to claim 1 wherein:

the volumetric ratios of the volumes of the liquid cylinder and the air cylinder between the base and peak of the stroke cycles is between 1:1-20.

3. The foaming pump mechanism according to claim 1 wherein:

the volumetric ratios of the volumes of the liquid cylinder and the air cylinder between the base and peak of the stroke cycles is between 1:5-15.

4. The foaming pump mechanism according to claim 1 wherein:

downstream of the bore of the liquid cylinder is present a liquid outlet valve which comprises: a valve bore, a biasing spring, a bore shoulder, a valve seat and a valve mounted on a valve shaft said valve shaft extending into the bore.

5. A dispenser for providing a foam to a user which comprises:

a reservoir which forms part of the dispenser, and

a foaming pump mechanism according to claim 1 .

6. The dispenser according to claim 5 wherein the reservoir is a refill unit insertable into a base of the dispenser.

7. The dispenser according to claim 5 , wherein the dispenser initiates dispensing by a non-contact interaction with the user.

8. The dispenser according to claim 5 wherein the foaming pump mechanism is manually powered.

9. The dispenser according to claim 5 wherein the foaming pump mechanism is driven by a motor.

10. The foaming pump mechanism according to claim 3 further comprising a liquid outlet valve, located downstream of the bore of the liquid cylinder, wherein the liquid outlet valve comprises a valve bore, a biasing spring, a bore shoulder, a valve seat and a valve mounted on a valve shaft said valve shaft extending into the bore.

11. The foaming pump mechanism according to claim 10 , wherein the dispensing nozzle includes only a single screen.

12. The dispenser according to claim 5 , wherein the volumetric ratios of the volumes of the liquid cylinder and the air cylinder between the base and peak of the stroke cycles is between 1:5-15.

13. The dispenser according to claim 12 , wherein the reservoir is a refill unit insertable into a base of the dispenser.

14. The dispenser according to claim 12 , wherein the dispenser initiates dispensing by a non-contact interaction with the user.

15. The dispenser according to claim 12 , wherein the foaming pump mechanism is manually powered.

16. The dispenser according to claim 12 , wherein the foaming pump mechanism is driven by a motor.